A voltage converter designed as a constant voltage converter provides a DC voltage of, e.g., 12 volts or 24 volts at its output. LED modules can be connected to the output of this converter, which have typically implemented a simple current regulation, e.g. by means of an analog current regulator.
When operating LEDs, the voltage generated by the voltage converter and applied to the LEDs must be sufficiently high. This voltage should be higher than the flux voltage for the LEDs, in order to illuminate the LEDs.
The output voltage of the voltage converter must thus be selected such that, on one hand, the flux voltage of the LED module is obtained, and on the other hand, it should not be too high above the flux voltage of the LED strip, because otherwise unnecessary electrical energy must be dispelled in the current regulator.
An adaptive voltage converter is known from the prior art, DE 10 2006 000 810 D4, wherein the adaptability in this regard is to be understood to mean that when the voltage converter is switched on, it increases its DC output voltage constantly, until a current flow is detected by the LED strip connected thereto. The voltage converter then maintains the output voltage at a steady level, at which it can detect the current flow.
The fact that the setting of the output voltage can only occur when the voltage converter is switched on is a disadvantage in this prior art. It is, in fact, necessary for this adjustment to change the output voltage from a first value lying below the flux voltage to a second value lying above the flux voltage, wherein the output voltage is kept constant after a current flow has been detected. In order to be able to execute a further adjustment while the LED strip is in operation, the LED strip must first thus be switched off, and the output voltage must again be slowly increased from a first value lying below the flux voltage. This would result in a shutting off of the LED strip during the time used for adjusting the output voltage while the LED strip is in operation, which is, of course, not desired.
On the whole, the output voltage can only be adjusted once according to the prior art, such that the power losses in the current regulator are minimized. This power loss, however, can again increase during operation, e.g. because the voltage drop from LEDs—the so-called flux voltage—can fluctuate, in particular as a result of temperature changes.
Given this problem, the object of the present invention is to be able to minimize the power losses and the accompanying heat development, not only when the voltage converter is switched on, but also at a later point in time, when the LED strip is already switched on. An adjustment of the output voltage of the voltage converter should also be enabled, accordingly, during operation of the LED strip.